1. Field of the Invention
The invention relates to a contact element which may be anchored in a plastic base body for a relay, especially in a printed-circuit board relay, the contact element forming a connecting pin with at least one end section. In this case, the invention relates specifically to a contact element which is suitable for carrying large currents and is anchored in a base or a base plate, or even in a pocket in a coil former.
The invention furthermore relates to a method for producing such a contact element.
2. Description of the Related Art
Wire spring contacts are already known, for example from German Published Application 21 02 651. However, the wire springs disclosed therein are of relatively thin cross-section and in addition both the moving contact elements and the mating contact elements are constructed as long springs, as a result, there is a relatively high resistance between the contact point and the connecting pin, so that only small currents can be switched. This results from the fact that the springs are of round cross-sections which rest across one another in the contact region so that contact there between is only in the form of points, which in turn means a high contact resistance and excludes the switching of large currents.
This also applies essentially to wire spring contacts as are known from German Published Application 11 41 717. Reinforcement of the contact points is provided there in such a manner that the ends of the wires are bent at the contact point and thus rest on one another in a doubled manner. Nevertheless, the contacts there are in the form of points between thin wire cross-sections.
Short, round connecting pins are also known having glass bushings in bases of hermetically sealed relays as hown in German Published Application 16 15 838), but the round connecting pin there does not itself form the contact element. Instead, one additional contact spring element is welded onto the round connecting pin in the interior of the relay.
A relay is already known from U.S. Pat. No. 3,624,571 in which contact elements which are movably mounted in the base have a round cross-section and are stamped flat on their contact-making ends. However, the contacts disclosed therein are not sufficient for carrying large currents.
It is also normal in the case of reed contacts to provide the sections of the contact tongues which are fused into a small glass tube with a round cross-section, whilst the contact regions themselves are flattened. However, such reed contacts have ferromagnetic contact tongues have relatively poor electrical conductivity which, in addition, also are not formed into soldering pins for insertion into a printed-circuit board at their connecting sections. Such contact tongues would likewise not be suitable for use in a relay for switching high currents.
Similar contact tongues are also shown in French Published Application 2,389,989, in which the end of a spring tongue is in each case stamped and is provided with a contact piece. Once again only the cross-section of an elongated wire spring is available for passing current.
The problem in the case of the contact elements considered here is that simple small relays for switching high currents, as are used for example in motor vehicles, require mating contact elements having large cross-sections. As a rule, these mating contact elements are cut from a flat strip of material, and flat plugs having the same rectangular cross-section, or a rectangular cross-section of similar size, are integrally formed on the connecting of the flat strip side. If it is intended to place such relays on printed-circuit boards, then it is normal procedure to construct short soldering pegs on the ends of the flat plugs by cutting the strip of material, thereby forming soldering pegs can be inserted into soldering perforations in the printed-circuit board. Such soldering perforations in the printed-circuit boards are, however, virtually without exception drilled in order to ensure that they have relatively smooth walls and are free of stress cracks. A soldering peg which is formed by cutting a flat strip has, however, a square or rectangular cross-section which does not completely fill the round hole so that not only is a part of the possible cross-section lost for passing current, but the reliability of the connection on the printed-circuit board is also reduced.